Blockchain Ballots

A decentralized voting system built on Ethereum, developed during a hackathon. Voters cast ballots through a React frontend that interacts with a Solidity smart contract, which enforces single-vote semantics, supports vote delegation, and tallies results entirely on-chain.

Features

• On-chain vote recording — ballots are stored on Ethereum, providing a transparent and tamper-resistant audit trail
• Double-vote prevention — the smart contract enforces one vote per address
• Vote delegation — voters can delegate their voting power to a trusted proxy, with loop protection
• Real-time tallying — winner determined directly from on-chain state
• Event-based audit trail — GaveRight, Delegated, Voted, and UpdatedMessages events emitted for off-chain indexing

Tech Stack

Layer	Technology
Frontend	React, React Router
Backend	Flask
Blockchain Interaction	Web3.js
Smart Contracts	Solidity (0.5.x), Truffle
Local Chain	Ganache
Hosting	Firebase Hosting

Architecture

React UI (browser)
  → Web3 provider (Ganache / MetaMask)
    → Ballot smart contract (Solidity)
      → On-chain state + events

Smart Contract Design

The Ballot contract manages the full voting lifecycle:

Data model

• chairperson — deployer address with administrative authority
• proposals[] — list of candidates/options, each with a voteCount
• voters[address] — per-voter record tracking weight, delegation, and vote status

Core functions

Function	Purpose
constructor(bytes32[], string)	Initializes ballot with proposals and sets deployer as chairperson
giveRightToVote(address)	Grants voting rights to an address
delegate(address)	Delegates voting power with circular-delegation protection
vote(uint)	Casts a vote and increments the selected proposal's count
winningProposal() / winnerName()	Returns the current winner from on-chain state

Voting flow

1. Contract is deployed with a list of proposals
2. Chairperson grants voting rights to eligible addresses
3. Voters either vote directly or delegate to another address
4. Contract enforces single-vote semantics and updates counts on-chain
5. Anyone can query the winner via winnerName()

Project Structure

.
├── migrations/               # Truffle migration scripts
├── public/                   # Static assets
├── src/
│   ├── abis/                 # Truffle build artifacts (ABI + bytecode)
│   ├── components/           # React UI (Home.js, Voting.js)
│   └── contracts/            # Solidity smart contracts
├── truffle-config.js         # Truffle network + compiler settings
└── firebase.json             # Firebase Hosting config

Local Development

Prerequisites: Node.js, npm, Ganache (or another local Ethereum RPC on port 7545), and optionally MetaMask

# Install dependencies
npm install

# Start Ganache on http://127.0.0.1:7545

# Compile and deploy contracts
npx truffle compile
npx truffle migrate --reset

# Start the frontend
npm start
# UI available at http://localhost:3000

Future Improvements

• Integrate formal identity verification (current UI has a webcam placeholder)
• Add privacy-preserving voting (e.g., zero-knowledge proofs) — votes are currently public on-chain
• Implement end-to-end cryptographic auditability
• Deploy to an Ethereum testnet for broader testing